Rotary displacement machine



Dec. 6, 1966 P. MULLER 3,

ROTARY DISPLACEMENT MACHINE Filed Dec. 4, 1964 8 Sheets-Sheet 1 FIG. 7

mm III/14mm Dec. 6, 1966 P. MULLER 3,289,652

ROTARY DISPLACEMENT MACHINE Filed Dec. 4, 1964 8 Sheets-Sheet 2 Dec. 6,1966 P. MULLER 3,289,652

ROTARY DISPLACEMENT MACHINE Filed Dec. 4, 1964 8 Sheets-Sheet 5 Dec. 6,1966 P. MULLER 329,652

ROTARY DI SPLACEMENT MACHINE Filed Dec. 4, 1964 8 Sheets-Sheet 4;

Dec. 6, 1966 P. MULLER ROTARY DISPLACEMENT MACHINE Fi led Dec. 4, 1964 8Sheets-Sheet 5 FIG. 9

Dec. 6, 1966 P. MULLER 3,289,652

ROTARY DISPLACEMENT MACHINE Filed Dec. 4, 1964 8 SheetsSheet 6 Dec. 6,1966 P. MULLER 3,289,652

ROTARY DISPLACEMENT MACHINE Filed Dec. 4, 1964 8 Sheets-Sheet '7 l//'lf4///// 1966 P. MULLER 3,289,652

ROTARY DISPLACEMENT MACHINE Filed Dec. 4, 1964 8 Sheets-Sheet 8 UnitPatented Dec. 6, I966 tire The present invention relates to a rotarydisplacement machine one member of which has an oval or polygonalprofile. The circumferential surface of said profile is provided withsealing elements guided in the other member of the displacement machineso as to be radially movable relative thereto. These sealing elementsdivide the space between the oval or polygonal member and the othermember of the rotary displacement machine into at least four workingchambers, the arrangement being such that in every other working chamberthere will prevail a different phase of the fluid pressure conditionthan does prevail at the same time in the working chambers therebetween.

Rotary displacement machines of this type frequently together withreciprocatory piston displacement machines form movement converters forconverting a recipnocatory movement to a rotary movement and vice versa.Movement converters in combination with oscillating fluid columnsforming a hydraulic linkage, are employed to great advantage withinternal combustion engines in substitution for customary crank drives.

Rotary displacement machines of the above-mentioned type have thedrawback that the sealing elements during the operation of the machineshave to move out of their slots to a considerable extent, so that greatforces have to be transmitted in tangential direction and the respectivedisplacement part in said slots as well as the sealing elements aresubjected to great stresses and consequently are subject to rapid 'wear.In addition thereto, care has to be taken in order to prevent thesealing elements from being lifted by the fluid pressure off thecircumferential surface of the displacement part.

It is, therefore, an object of the present invention to provide a rotarydisplacement machine which will overcome the above-mentioned draw-backs.

It is another object of this invention to provide a rotary displacementmachine with sealing elements adjacent the periphery of the rotatingmember of the machine, in which the sealing elements will not besubjected to any high stress and thus will not be liable to wearrapidly.

These and other objects and advantages of the invention will appear moreclearly from the following specification in connection with theaccompanying drawings, in which:

FIGURE 1 illustrates in section a movement converter with a rotarydisplacement arrangement according to a first embodiment of theinvention, said section being taken along the line II of FIGURE 2;

FIGURE 1a is a section of a part of the movement converter accordingFIGURE 1 on a larger scale;

FIGURE 2 represents a section taken along the line II-II of FIGURE 1;

FIGURE 3 is a section taken along the line III-III and in part along theline III-IIIa of FIGURE 1;

FIGURES 4, 6, 7 and 9 illustrate in cross-section further embodiments ofa rotary displacement machine according to the invention;

FIGURE represents a section taken along the line V-V of FIGURE 4;

FIGURE 8 is a section taken along the line VIII-VIII of FIGURE 7;

FIGURE 10 illustrates a section along the line XX of FIGURE 9;

FIGURES ll and 12 illustrate in cross-sections movement convertersaccording to further embodiments of the invention;

FIGURE 13 shows a part of a rocker according to a particularconstruction, in a perspective view.

The present invention consists primarily in that with a rotarydisplacement machine of the abovementioned type, rockers are employedfor guiding the sealing elements, each rocker having at least onesealing element in engagement with the profiled structural surface ofone rotary displacement member, whereas the remaining sealing elementsengage cylinder surfaces of the other displacement member, said cylindersurfaces being concentric to the rocker axis. According to a furtherfeature of the present invention, the edges of the sealing elementsconfine four surfaces perpendicular to which act the resultants of theliquid pressures prevailing between the respective edges. Of said foursurfaces, each surface equals that of the respective oppositely locatedsurface, and the pressure acting upon one surface equals the pressureacting upon the respective oppositely located surface. Preferably, thecontacting edges of the four sealing elements of each rocker form aprism with rectangular base surface. In many instances, the arrangementis such that the edges of the four sealing elements of each rocker arelocated on one and the same circular cylinder coaxial to the axis of therespective rocker.

For instance, each rocker is equipped with two sealring elementsengaging the profiled structural surface of a displacement member. Inthis instance, the oscillating movements of the rocker are effectedpositively in response to a rotation of one of said displacementmembers. In this connection, it is assured that the sealing elementscannot lift themselves off the profiled circumferential surface of onedisplacement member. However, there exists an interdependency betweenthe profile of the above-mentioned circumferential surface on one handand the distance between the sealing elements engaging saidlast-mentioned surface, and the location of the rocker axis on the otherhand. However, to assure that the respective sealing elements safelyengage the profiled circumferential surface, also additional auxiliarymeans such as springs may be employed.

For instance, the shaft of each rocker may form a chamber housing saidrocker and pertaining to one displacement member extend to the outsideof said chamber and may be provided with an arm the end of which may,for instance through the intervention of a roller carried thereby firmlyengage a cam connected to the other dis placement member. The said camis so profiled that the respective sealing element will at all timesengage the profiled structural surface of said other displacementmember. In this way, the rockers are positively guided. This guidedmotion may be discontinued by causing the said cam disc to disengage theroller of the arm carrying the latter. This is effected, for instancewith a hydraulic linkage replacing a mechanical crank drive, between areciprocable displacement machine and a rotary displacement machinewhenever it is desired to disconnect the respective output shaft.

Referring now to the drawing in detail and FIGS. 1 to 5 thereof inparticular, the housing of the movement converter illustrated thereincomprises a central member I which houses two cylinders 2 and 3 of areciprocatory piston displacing machine. Provided between said twocylinders 2 and 3 there is a circular cylindrical chamber 4 forreceiving a rotor 5. Each end face of said central member 1 has flangedthereto cover 6 and 7 respectively. Rotor 5 has an oval profile which issymmetrical with regard to two diameters arranged at a right angle withregard to each other. As will be seen from the drawing, rotor isprovided at each side thereof with a cylindrical extension 8 whichextensions are by means of bearing boxes 9 journalled in the housingcovers 6 and '7. Each extension 8 is provided with teeth 11} by means ofwhich rotor 5 may be connected to rotors of movement converters.

The space confined by the circumferential surface of chamber 4 is bymeans of sealing elements to be described further below subdivided intofour working chambers 11, 12, 13 and 14 each of which extends over aquarter of the circular circumference of chamber 4. Chambers 11 and 13located diametrically opposite to each other communicate with cylinders2 through passages 15, 16. The other two diametrically oppositelylocated working chambers 12 and 14 communicate with cylinder 3 throughpassages 17, 18.

Within the working chambers 12, 14 there are respectively providedrockers 19, 20. Each rocker is at opposite sides thereof journalled inbores of the housing covers 6 and 7. More specifically, the upper rocker19 is journalled in covers 6, 7 by means of stud 21 and a shaft 22protruding from cover 7. The lower rocker is similarly journalled. Eachof the rockers 19, 20 has two lateral extensions 22a interconnected by ayoke 23. The said lateral extension-s 22a have substantially the samewidth as the central member 1 (see FIG. 3) and have their end faces inclose engagement with respectively adjacently arranged sealing rings 24inserted in the respective adjacent surfaces of the covers 6, 7. Thesaid sealing rings 24 are arranged coaxially with regard to the axis 26of the rocker and have their inner ends in close engagement with sealingmembers 25 (see FIG. 1) which latter are provided in grooves of bearingbores or bushings 9.

Those marginal portions of yokes 23 of rockers 19, 20 which face rotor 5are provided with grooves having arranged therein sealing strips 27(FIG. 1) which are displaceable in radial direction to a slight extent.These strips 27 have their edges in engagement with the circumferentialsurface of rotor 5 and have their end faces in engagement with sealingrings 24.

Yokes 23 of rockers 19, 20 are furthermore provided with grooves havingslightly displaceably guided therein sealing strips 28 (FIG. 1). Sealingstrips 28 have their edges in engagement with surfaces 29 which arecurved along the contour of a cylinder coaxial with the respectiverocker axis 26. Said surfaces 29 pertain to rail bodies 30 which areinserted in transverse bores of the central member 1. The bodies 311 aresecured against rotation by pins 31.

As Will be evident from the above, sealing strips 27, 28 divide andseparate the working chambers 12, 14 respectively containing rockers 19,20 from the other working chambers 11, 13 which extend up to the sealingstrips 28 in narrow gaps between yokes 23 and closure bodies 30. Thearrangement of the sealing strips is such that the edge of each strip 27is diametrically oppositely located with regard to a strip 28, and thatthe edges of all four sealing strips of each rocker are located on acircular cylinder (FIG. 1a) coaxial with regard to the axis of therespective rocker. Thus, the four points which in FIG. 1 represent theedges of the sealing strips 27, 28 are located in the corners of a rightangle. Consequently, the forces exerted on each rocker on one hand bythe liquid pressure in working chambers 11 and 13, and on the other handby the liquid pressure in working chambers 12 and 14, balance eachother. The bearings of rockers 19, 20 are, therefore, not under the loadof liquid pressures.

Sealing strips 27, 28 may, if so desired, be pressed against therespective counter surfaces by springs (illustrated) in the groovespertaining thereto. However, it is also possible to replace the thrustof the springs by hydraulic pressure. To this end, yokes 23 (as shown inFIG. 1 in the lower left-hand yoke) may be provided with bores 32, 33which connect the grooves containing the sealing strips through adouble-acting check valve 34 alternately with one or the other of thetwo adjacent working chambers, for instance 11, 14, and, morespecifically, each time with that working chamber in which the higherpressure prevails.

Shaft 22 which pertains to rocker 19 and protrudes from the housing mayserve for driving an auxiliary device, for instance an injection pump ordischarge valves or a cooling pump. It is also possible, forinstallation purposes, to journal rockers 19, 20 unilaterally only inthe housing.

As will be evident from FIG. 3, housing covers 6, 7 may be centered withregard to the central member 1 by means of sleeves 35 which are equippedwith sealing rings 36 and at the same time serve as gap bridges, forinstance for passage 18.

Referring now to FIGS. 4 to 10, each rocker, for instance rocker 40 ofFIGS. 4 and 5, has only one sealing strip 41 for engagement with thecircumferential surface of rotor 5, whereas the other sealing strips 42,43 and 44 engage cylindrical surfaces 45, 46 the axes of curvature ofwhich coincide with the axis of rocker 47. The edges of sealing strips41, 42, 43 and 44 form the sides of a prism with a rectangular basesurface. The large sides of the rectangle between the edges of strips41, 43 and 42, 44 are designated with the letter a, whereas the smallsides of the rectangle between the edges 41, 44 and 42, 43 have beendesignated with the letter b. Sealing strip 41 separates two workingchambers 12, 13 of the rotary displacement device from each other.Working chamber 12 communicates through a passage 48 in rocker 41) withthe oppositely located chamber in housing 1, whereas working chamber 13merges with the narrow gap between the rocker and the cylindricalsurface 46 and through a passage 49 in said rocker communicates with theoppositely located annular gap between sealing strips 42, 43.

Consequently, between strips 41, 44 and 42, 43 on one hand, and betweenstrips 41, 43 and 42, 44 on the other hand through liquid pressures inworking chambers 12 or 13 no moment acts upon rocker 40 so that a weakspring 70 will suffice to assure engagement of sealing strip 41 withrotor 5.

As will be evident from FIG. 5, rocker 40 is journalled in housing 1 bymeans of two studs 51 which are not loaded by the liquid pressure inchambers 12, 13. The end faces 51 of rocker 40 closely engage the endfaces of the recess of housing 1 receiving rocker 40.

According to the embodiment of FIGS. 4 and 5, the rocker axis is locatedin the point of intersection of the diagonals of the rectangle a, b, or,differently expressed, the edges of the four sealing elements 41, 42 and43, 44 are located on a circular cylinder coaxially arranged with regardto the rocker axis 47.

The embodiment according to FIG. 6 differs from that of FIGS. 4 and 5merely in that the axis of rotation 52 of rocker 53 is not located inthe point of intersection of the diagonals of that rectangle which inthe illustrated cross-section is formed by the edges of sealing strips41, 42, 43, 44. Instead, the radius of the cylindrical surface 54engaged by sealing strips 42, 43 is with regard to rocker axis 52considerably smaller than the radius of the cylindrical surface 55engaged by sealing strip 44. However, rocker axis 52 is located in therocker central plane which halves the arc of a circle between thesealing strips 42, 43 on one hand and the sealing strips 41, 44 on theother hand. (If axis 52 would be located outside said plane, the sealingstrips 42, 43 would have to engage the cylindrical surface withdifferent radii of curvature).

Consequently, the long sides a of the rectangle defined by the strips41, 42, 43, 44 are with the embodiment of FIG. 6 shorter than thecorresponding sides a of the rectangle in the embodiments of FIGS. 4 and5, whereas the short sides b of the rectangle may have the same size.Therefore, in order to house rocker 53 of FIG. 6 in housing ll, lessspace is required than is the case with the embodiment of FIGS. 4 and 5.

A further saving in space can be obtained when in conformity with FIGS.7 and 8, the arc of a circle between the sealing strips 42, 43 isselected shorter than the distance between sealing strips 41, M. In thisinstance, the four edges of the guiding strips are not located on arectangle but on a quadrangle the short sides I)" of which between theedges of strips 42, 43 are shorter than side 12 located between theedges of strips 41, 44. In this connection, it should be noted thatsides a pertaining to the quadrangle and located between the edges ofstrips 42, 44- and 4d, 43 are shorter than the sides of a of therectangle according to FIG. 6. Thus, the chamber of housing 1 whichreceives the rocker 56 is shortened further. In order to assure thatnevertheless the liquid pressures in chambers 12 and 13 will upon rocker56 not exert any forces to be absorbed by the rocker bearings, thesurface between sealing strips 42, 43 is made equal to the effectivesurface between sealing strips 41, 44. This is realized by making rocker56 (see FIG. 8) within the range of sealing strips 42, 43 longer inaxial direction than in the direction of strips 41, 44. The length ofrocker 56 in the two rnentioned ranges has been indicated by the lettersa and 0, respectively. Thus, b" d=b c. With this design of the rocker,bearing studs corresponding to studs 50 in FIG. become superfluous andmay be omitted.

FIGS. 9 and 10 illustrate an embodiment according to which rocker which,for instance is designed in the same way as the rocker according toFIGS. 4 and 5, is automatically during the rotation of rotor 5 soactuated that sealing strip 41 will always engage the circumferentialsurface of rotor 5. To this end, outside housing 1 and on one of bearingstuds 56 (FIG. 10) extending through said housing and pertaining torocker 4%, there is provided an arm 57 one end of which carries a roller5%. Roller 58 engages the circumferential surface 59 of a cam 60 whichlatter is non-rotatably but axially displaceably mounted on an outputshaft 61 carrying rotor 5. Surface 59 is similar to the circumferentialsurface of rotor 5, and the axes of symmetry of said surface have, withregard to the axis of rotation, the same location as the axis ofsymmetry of rotor 5. The effective lever length of arm 57 is, in View ofthe lever arm of the edge of strip 41 with regard to rocker axis 47 sodimensioned that during the rotation of rotor 5 and cam 6t), sealingstrip 41 will always be held in engagement with the circumferentialsurface of rotor 5. Inasmuch as the liquid pressures acting upon rocker40 are at all times completely balanced, the members 59, 57 and 58, 60have to convey only minor adjusting forces and consequently, can be ofcorrespondingly light structure. Cam 60 may be adapted to any desiredrotor shapes and may be exchanged for corresponding cams when otherrotors are employed.

It is possible to displace cam 60 to the position illustrated bydot-dash lines in FIG. 10. If such a displacement takes place, roller 58disengages cam surface 59 so that rocker 40 will no longer automaticallybe moved in conformity with the rotation of rotor 5. In this instance,rocker 40 may by means of a spring be tilted in such a way that sealingstrip 41 disengages the circumferential surface of rotor 5.Consequently, it is at the operators discretion to nullify the effect ofthe rotary displacement device so that it will not convey any torques.This is of importance above all when a hydraulic linkage of an internalcombustion engine is involved because in this instance it is easier tointerrupt the power transmission between a cylinder pair of the machineand the output shaft. As a result thereof it is possible, for instanceto repair individual cylinders of a multi-cylinder internal combustionengine while the remaining cylinders continue in operation.

The present invention also :covers an arrangement according to whichrockers with one sealing element each which engages the rotor-forinstance in conformity with the embodiments of FIGS. 5 to 10'tredistributed in such a number over the circumference of the displacementchamber housing the rotor as is required when more than two reciprocablepiston displacement devices are con nected to a rotary displacementdevice. This may be the case for internal combustion engines composed ofa plurality of driving units in conformity with the building blockprinciple, of which each driving unit consists of three or morecylinders and a rotary displacement device and also has a waste gasturbo-charger. Inasmuch as in this instance, three or more cylinderswork upon a charger at a corresponding phase development of less than180, more favorable charging conditions are obtained. An embodiment withsix rockers 4t) and three reciprocable piston dispiacement devices 71,72, 73 is illustrated in FIG. 11.

FIG. 12 shows a further embodiment with a rotor 74- ofcircle-cylindrical form whereas the housing 75 has an oval profile. Tworockers 76 are journalled within holes of the rotor 74. By means ofconduits '77, 7t; fiuid is led to chambers 79, 8d and by means ofconduits $1, 82; from chambers 83, 8d, and vice versa. It is possiblethat the rotor 74, rotates and the housing 75 stands still or that therotor 74 stands still and the housing 75 rotates.

Similarly, with an embodiment having an oval rotor and acircle-cylindrical housing the latter may rotate whereas the rotorstands still.

Furthermore, when more than two cylinders work on one rotarydisplacement device, a greater rotor diameter is obtained by the sameoutput weight. As a result thereof, a greater flexibility is obtainedwith regard to the construction of the coupling elements whichinterconnect the rotors of the driving units. The sealing strips do nothave to be rectilinearly parallel to the rocker axis but may also behelical. FIG. 13 shows a helical sealing strip 85 arranged in a nut of arocker 19.

It is, of course, to be understood that the present inventionis by nomeans limited to the particular constructions and arrangement shown inthe drawings, but also comprises any modifications within the scope ofthe appended claims.

What I claim is:

I. In a rotary displacement machine, housing means comprising chambermeans 'having at least four working chambers which are connected to thecylinders of reciprocating displacement means so that each workingchamber at any one time is in a different phase of change in liquidpressure from the adjacent working chambers, rotor means rotatable insaid chamber means, the peripheral surface of said rotor means having atleast two planes of symmetry and having different radii in said planesof symmetry, certain of said working chambers having cylindrical wallsurface portions, rocker means pivotally mounted in each of said certainworking chambers on an axis concentric with said cylindrical surfaceportions and engaging said rotor means to separate its working chamberfrom an adjacent chamber, each of said rocker means having four sealingmeans, said sealing means being spaced about the periphery of saidrocker means at points defining a quadrilateral, certain of said sealingmeans engaging the rotor means and the others engaging the cylindricalwall surface portions, said sealing means confining two pairs ofsubstantially equal and opposite surface sections on said rocker maens,the pressures on each pair of opposite surface sections beingsubstantially equal and opposite so that the fluid pressure exerts aminimum force on the mounting of said rocker means.

2. In the machine defined in claim 1, in which a shaft is connected tosaid rocker means and extends through said housing means to the outside,cam means are arranged on the outside of said housing means andnonmotatably connected to said rotor means and means are connected tosaid shaft and engage said cam means, said cam means being shaped tohold said sealing means positively in engagement with the respectivesurfaces to be engaged.

3. In the machine define-d in claim 1, in which one of said rocker meansis connected to a shaft extending through said housing means to theoutside for connection with an auxiliary means to be driven by saidrocker means and in which the surface sections of each pair of oppositesurface sections are substantially the same size.

4. In the machine defined in claim 1, in which said housing means isformed by an annular central member and two cover means connected toopposite sides of said central member to form said chamber means andsaid rocker means are mounted in said cover means, and sealing ringmeans are supported by said cover means substantially coaxial with theaxis of said rocker means for effecting a seal between said cover meansand the respective adjacent sealing means.

5. A rotary displacement machine according to claim 1, in which at leastsome of said cylindrical wall surface portions are formed by Wearelements inserted into said housing means.

6. In a rotary displacement machine, housing means comprising chambermeans having at least four working chambers which are connected to thecylinders of reciprocating displacement means so that each workingchamber at any one time is in a different phase of change in liquidpressure from the adjacent working chambers, rotor means rotatable insaid chamber means, the peripheral surface of said rotor means having atleast two planes of symmetry and having different radii in said planesof symmetry, certain of said working chambers having cylindrical Wallsurface portions, rocker means pivotally mounted in each of said workingchambers on an axis concentric with said cylindrical surface portionsand engaging said rotor means to separate its Working chamber from anadjacent chamber, each of said rocker means having four sealing means,said sealing means being spaced about the periphery of said rocker meansat points defining a quadrilateral, two of said sealing means engagingsaid rotor means and confining one surface section on said rocker meanstherebetweeen and two of said sealing means engaging said cylindricalwall surface portions and confining a surface section on said rockermeans equal and opposite said one surface section therebetween, eachpair of sealing means engaging with the rotor means and a cylindricalwall surface portion confining one of two equal and opposite surfacesections on said rotor means, the pressures on each pair of oppositesurface sections being substantially equal and opposite so that thefluid pressure exerts a minimum force on the mounting of said rockermeans.

7. In a rotary displacement machine, housing means comprising chambermeans having at least four working chambers which are connected to thecylinders of reciproeating displacement means so that each workingchamber at any one time is in a different phase of change in liquidpressure from the adjacent working chambers, rotor means rotatable insaid chamber means, the peripheral surface of said rotor means having atleast two planes of symmetry and having different radii in said planesof symmetry, certain of said working chambers having cylindrical wallsurface portions, rocker means pivotally mounted in each of said certainWorking chambers on an axis concentric with said cylindrical surfaceportions and engaging said rotor means to separate its working chamberfrom an adjacent chamber, each of said rocker means having four sealingmeans, said sealing means being placed about the periphery of saidrocker means at points defining aquadrilateral, one of said sealingmeans engaging said rotor means and the others engaging the cylindricalwall surface portions, one pair of circumferentially spaced sealingmeans confining one surface section of said rotor means therebetween andthe other pair of circumferentially spaced sealing means confining theequal and opposite surface section on said rotor therebetween, thesealing means forming each of the other two pairs confining one of twoequal and opposite surface sections on said rotor means, the pressureson each pair of opposite surface sections being substantially equal andopposite so that the fluid pressure exerts a minimum force on themounting of said rocker means.

8. In the machine defined in claim 7, in which one of the oppositesurface sections confined by one of the last-named pairs of sealingmeans is of less width radially and greater length axially than theother of said pairs.

9. In a rotary displacement machine, housing means comprising chambermeans the circumferential surface of which have at least two planes ofsymmetry and different radii in said planes of symmetry, rotor meanshaving a cylindrical peripheral surface arranged within said housingmeans for relative rotation between said housing means and rotor means,said rotor means having a plurality of recesses open to said chambermeans and equally spaced about said peripheral surface, each recesshaving two cylindrical wall surface portions, a plurality of rockermeans each mounted within one of said recesses for rocking movementabout an axis concentric With said cylindrical Wall surface portions,each of said rocker means having four sealing means at least one ofwhich is in engagement with said circumferential surface of said housingmeans and the others in engagement with the wall surface portions, sothat said chamber means is divided into four working chambers, saidworking chambers being connected to the cylinders of reciprocatingdisplacement means so that each Working chamber is at any time in adifferent phase of change in liquid pressure from the adjacent chambers.

10. In a rotary fluid displacement machine having a housing meanscomprising a plurality of Working chambers, and a rotor means in saidhousing means the peripheral surface of which has at least two planes ofsymmetry and different radii in said different planes, so that thevolumes of said working chambers increases and decreases With rotationof said rotor means, cylindrical wall surface portions in one of saidWorking chambers, a rocker means pivotally mounted in said one workingchamber on an axis concentric with said cylindrical surface portions andengaging said rotor means to separate fluid in said one working chamberfrom an adjacent chamber, said rocker means having four sealing meansengaging said rotor means and said curved surface portions, said sealingmeans being located at points at the corners of a quadrilateral whichencloses said pivotal axis, the opposite sides of said rocker meansbetween the pairs of sealing means at circumferentially spaced pointsbeing equal and subjected to the fluid pressure in said working chamberin opposite directions inwardly of said rocker means, and the oppositesides of said rocker means between the pairs of sealing means atradially spaced points being equal and subjected to equal fluid pressurein opposite directions from at least one adjacent chamber so that thefluid pressures are substantially equal and opposite on said rockermeans.

References Cited by the Examiner UNITED STATES PATENTS 781,342 1/1905Hoffman 91l09 X 1,655,738 1/1928 Rasck 91l09 2,218,573 10/1940 Gahm91-109 X FOREIGN PATENTS 105,306 9/1899 Germany.

274,402 7/1927 Great Britain.

MARK NEWMAN, Primary Examiner.

F. T. SADLER, Assistant Examiner.

1. IN A ROTARY DISPLACEMENT MACHINE, HOUSING MEANS COMPRISING CHAMBERMEANS HAVING AT LEAST FOUR WORKING CHAMBERS WHICH ARE CONNECTED TO THECYLINDERS OF RECIPROCATING DISPLACEMENT MEANS SO THAT EACH WORKINGCHAMBER AT ANY ONE TIME IS IN A DIFFERENT PHASE OF CHANGE IN LIQUIDPRESSURE FROM THE ADJACENT WORKING CHAMBERS, ROTOR MEANS ROTABLE IN SAIDCHAMBER MEANS, THE PERIPHERAL SURFACE OF SAID ROTOR MEANS HAVING ATLEAST TWO PLANES OF SYMMETRY AND HAVING DIFFERENT RADII IN SAID PLANESOF SYMMETRY, CERTAIN OF SAID WORKING CHAMBERS HAVING CYLINDRICAL WALLSURFACE PORTIONS, ROCKER MEANS PIVOTALLY MOUNTED IN EACH OF SAID CERTAINWORKING CHAMBERS ON AN AXIS CONCENTRIC WITH SAID CYLINDRICAL SURFACEPORTIONS AND ENGAGING SAID ROTOR MEANS TO SEPARATE ITS WORKING CHAMBERFROM AN ADJACENT CHAMBER, EACH OF SAID ROCKER MEANS HAVING FOUR SEALINGMEANS, SAID SEALING MEANS BEING SPACED ABOUT THE PERIPHERY OF SAIDROCKER MEANS AT POINTS DEFINING A QUADRILATERAL, CERTAIN OF SAID SEALINGMEANS ENGAGING THE ROTOR MEANS AND THE OTHERS ENGAGING THE CYLINDRICALWALL SURFACE PORTIONS, SAID SEALING MEANS CONFINING TWO PAIRS OFSUBSTANTIALLY EQUAL AND OPPOSITE SURFACE SECTIONS ON SAID ROCKER MEANS,THE PRESSURES ON EACH PAIR OF OPPOSITE SURFACE SECTIONS BEINGSUBSTANTIALLY EQUAL AND OPPOSITE SO THAT THE FLUID PRESSURE EXERTS AMINIMUM FORCE ON THE MOUNTING OF SAID ROCKER MEANS.